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The last map class was not drawn at all; it was photographed, in rows, from an aeroplane — and for farm country it begins, as a federal programme, in the later 1930s. The mechanism is the record: from the mid-1930s the US Department of Agriculture photographed farm counties across the country to measure crop acreage for its farm programmes, county by county, in flights repeated over the following decades; the film's custody splits by date — the Farm Service Agency's Aerial Photography Field Office holds county film from the mid-1950s onward, and imagery before 1955 is directed by the agency's own catalogue to the National Archives, where USDA aerials sit in Record Group 145. For Indiana the index instrument is the Indiana Historical Aerial Photo Index (IHAPI), built by the Indiana Geological Survey: more than 950 large-format photomosaic index maps scanned and georeferenced into 466 county-based images dating from the 1930s to the 1980s, locating 113,016 individual historical aerial photographs statewide, 39,992 of them in the Survey's own archive — the tool that turns "the 1930s flights" into frame numbers over a named township.
Against that frame, this ground's own first flight is — honestly — not dated by this section. The county evidence reached runs to the wrong end of the county: the St. Joseph County Public Library's map case holds aerial photographs of Greater South Bend and Mishawaka dated 1937, 1939, 1941 and 1948, which prove USDA-era flying over the county's cities in the programme's first decade and prove nothing about the Lincoln Township frames. Whether Lincoln Township was flown in the same late-1930s county coverage, or first in a postwar flight, is a frame-level question the IHAPI index answers by township, range and section — the township here is 35 north, range 1 west, banked throughout this build — and it stands below as this item's named gap, with the strong probability, printed as probability and nothing more, that a farm township in a farm county was inside the early coverage rather than outside it. What the early frames would show, whenever they date from, is the aerial fact the banked Transportation leg already uses once: the lifted Kankakee Belt surviving "as a straight seam in the aerial photographs" — the one aerial observation the banked build makes, and the proof that this class is already load-bearing in the history, at line size, before this article.
The run's modern end is dated and public: the state's own orthophotography programme (the Indiana Geographic Information Office's statewide digital imagery, tiled statewide, collected on a four-year cycle by county tiers, with St. Joseph County in the central tier) runs from 2005 forward, and the USDA's NAIP county mosaics cover the county in the modern series (the 2010 Indiana NAIP coverage among the Field Office's published catalogues) — the photographic map become the base layer under the county GIS of the banked Neighborhoods leg, refreshed on a cycle, free to any reader. The aerial record's arc for this ground is therefore: a federal farm programme's film, an index that can name its frames, a first-flight date still to be pulled from that index, and a present in which the town is re-photographed from above more often than it is re-mapped on paper.
Closure: MIXED — the programme, custody, index and modern series DUG; Lincoln Township's first flight year a NAMED GAP. Settler: the Indiana Historical Aerial Photo Index (IGWS), queried for Township 35 North, Range 1 West, with the National Archives' Record Group 145 county list (Special List 25) behind it for pre-1955 film.
Sources: USDA Farm Service Agency, Aerial Photography Field Office, imagery catalogues (county coverage; pre-1955 imagery directed to the National Archives; NAIP Indiana 2010 catalogue), read for this section; Denver Harper, "Development of the Indiana Historical Aerial Photo Index," Indiana GIS Conference, 19 February 2008 (951 index maps; 113,016 photographs; IGS archive 39,992), read for this section; Indiana Geological and Water Survey, IHAPI description (466 county images, 1930s–1980s); SJCPL map case finding aid (Greater South Bend/Mishawaka aerials, 1937–1948); Indiana Statewide Digital Aerial Imagery Catalog, Registry of Open Data (state orthophotography from 2005; four-year cycle by tiers); Transportation leg of this build (the Belt's aerial seam).